Serosa

Serosa(orserous membrane) is a smooth membrane consisting of a thin layer ofcells,found on the outer wall of theorgansof theabdominalcavity known as the serous cavity. It secretes serous fluid, and a thinconnective tissuelayer. They secrete a lubricating fluid whichreduces frictionfrommusclemovement.

Serosa is not to be confused withadventitia,a connective tissue layer which binds together structures rather than reducing friction between them. The serous membrane covering the heart and lining themediastinumis called thepericardium,the serous membrane lining thethoracic cavityand surrounding the lungs is called the pleura, and that lining theabdominopelvic cavityand the viscera is called theperitoneum.

The portions of the gastrointestinal tract that do not have a serosa include the esophagus, as well as the middle and distal rectum.